Not started
External obligation, and the only form available in past and future.
Why you specifically
The rule
Have to is used for obligation, especially when the obligation comes from outside the speaker: rules, laws, schedules, employers, or other people. In the present simple, it changes like a normal verb: I/you/we/they have to, he/she/it has to. In questions and negatives, it uses do/does/did: Do you have to...?, I do not have to.... For past obligation, English normally uses had to. For future obligation, English normally uses will have to. That is why have to is especially useful: it covers present, past, and future more naturally than must. Compare it with must: must often means the speaker feels the obligation is strong or necessary. In everyday English, have to is more common for rules and outside requirements, while must is less common and more formal in many contexts.
Both correct
Every sentence here is correct English. Only the meaning changes.
I must finish this today.
Strong internal obligation or speaker-determined necessity.
I have to finish this today.
External obligation from a rule, schedule, or other person.
The trap
I must to wear a uniform at work.
I have to wear a uniform at work.
have to is the normal form for an obligation that comes from rules, an employer, a law, or a situation.
She must leave early because of the storm.
She had to leave early because of the storm.
In the past, obligation is normally expressed with had to, not must.
We must pay for the tickets tomorrow.
We will have to pay for the tickets tomorrow.
For future obligation, English uses will have to. Must is not the normal future form.
Have you to work on Saturday?
Do you have to work on Saturday?
Questions with have to are formed with do/does/did. You do not say have you to in modern English.
Prove it
10 drills
You have not fought this one yet.
Rivals
